Desulfurization of crude and cracked petroleum distillates



Feb. 7, 1950 c. o. HOOVER 2,496,536 DEsuLFURIzATIoN oF CRUDE AND cRAcKED PETROLEUM DISTILLATES Filed April 22, 1947 ATTORNEYS Patented Feb. 7, 195() UNITED STATES PATENT OFFICE nssuuunrzsnox or canne rs'rnouuun Ouml) AND ISTILLATES Charles 0. Hoover, Houston, Tex., assignor to Air Reduction Company, Incorporated,

New York,

N. Y., a corporation et New York Application April 28, 1047, Serial No. 743,170

. l This invention relates to the treatment of crude and cracked petroleum distiliates for thefrom such crudes and thus are found in the continuous manner to remove the sulfur content. v

Another object is the provision of a method of effecting regeneration of the treating material tc eliminate the sulfur, thus permitting reuse of the material without substantial loes.

Other objects and advantages of the invention will be apparent as it is better understood by reference to the following specification and the accompanying drawing, which illustrates diagrammatically an apparatus suitable for the practice of the invention.

The invention is applicable to crude and cracked petroleum distillates such as distillates from crude petroleum, kerosene. gasoline, gas oil and the like. It depends upon the treatment of such vapors with a treating agent. preferably copper, copper oxide or copper hydrate, in the presence of an aliphatic or aromatic carboxylic acid which is sumciently stable to permit vaporisation and which forms, with the copper compound, a copper soap or copper compound of the acid. Such a copper compound of the organic acid is adapted to combine with sulfur present in the vapors, releasing thereby the organic acid which immediately recombines with the copper compound to again react with sulfur in the vapors. The copper and such compounds thereof as will react with the organic acid to form a copper compound with which the sulfurous material contained in the distlllates will react to form stable copper-sulfur compounds are hereafter referred to as "cupreous material. As the result of these progressive reactions, the treating material acts progressively. that is to 1C Chill. (Ul. 19E-28) material first becomes eii'ective to remove sulfur, whereupon an overlying layer acts similarly, until the uppermost layer has been converted to a copper compound and has acted upon the vapors to remove the sulfur therefrom forming therewith stable copper-sulfur compounds. At this point, the material is no longer effective. It can.

however, be regenerated readily by first ilushixig with an inert gas to remove the hydrocarbon vapors and thereafter oxidizing the copper-sulfur compounds with oxygen or air suitably diluted with an inert gas in order to control the tem- .say,thelowermostlayerinacolumnoftheso perature of combustion. The combustion eliminates the sulfur, which escapes as sulfur dioxide, and the material is then in suitable condition for reuse in the operation.

The treating material may consist of copper in the metallic form such as turnings or small pieces. If copper in the form of a powder is used, or if copper oxide, either cuprous or cupric, or copper hydrate is employed, these materials are preferably formed into pellets with suitable additions such as alumina or clay or other ceramic materials which aord an adequate body and prevent disintegration and the production of lines. In case metallic copper is employed, it is preferably subjected initially to oxygen or air at an elevated temperature to partially oxidize the copper.

It is essential, in starting the operation, that an aliphatic or aromatic carboxylic acid be present to combine with the copper to form a copper compound of the acid. In many cases, the petroleum vapors include naphthenic acid, and if a sumcient proportion is present, no addition is necessary. Otherwise the acid should be introduced in the form of vapor in suillcient quantity to combine with the cupreous material in the lowermost layer of the treating material. Acetic acid may be employed instead of naphthenic acid. In fact, any of the aliphatic or aromatic carboxylic acids which are stable at vaporizing temperatures are suitable for use in the method. since it is necessary merely to have present a suiilcient amount of such an acid to form the copper compound which will react to combine with sulfur present in the vapors, forming water and releasing the acid for reaction with the overlying layer of the cupreous material.

The operation is conducted at an elevated temperature, suiiieient only to maintain the particular material treated in the vapor form. Thus, the temperature at the top of the column of the treating material may range approximately from decesso 400 to 800 F. Usually the temperaturerange is between 500 and 750 F. Lower or higher temperatures may be employed. depending upon the particular material which is treated.

In carrying out the invention. it is desirable to use two or more towers. in one or more of which the reaction is conducted while the spent material is re-oxidized in the other towers. Thus, the operation may be continuous. it being necessary merely to adjust the valves so that the vapors are directed through an operating column while the oxidizing gas is passed through the spent material.

Referring to the drawing, I and I represent towers of any suitable construction having grids l and 8 to support the treating material 9 and II which is preferably in the form of pellets or pieces of the same or varying size. Grids Il and I2 hold the treating material in the proper position.

A vaporizer or still I3 is adapted to hold the material to be treated and is heated in any suitable manner to provide vapor in a dome Il which is delivered through a pipe II controlled by a valve II or through a branch i1 controlled by a valve II to one or the other of the towers I and I. The towers are provided with drain outlets I9 and 20 controlled by valves 2i and 22 and with outlets 23 and 24 controlled by valves 25 and 2S. Through the latter outlets sulfur dioxide is permitted to escape during the oxidizing operation.

In the event that the material treated does not include a suilicient acid content, an acid vaporizer 21, which is adapted to be heated by a -ir provided with o branch u oontroned by a.

valve 21 which is connected to the tower I. A similar branch 28. controlled by a valve 29, is connected to the tower I. Similarly, a pipe 4I is connected to a source of oxidizing gas such as oxygen or air which is supplied through connections Il and 42 controlled by valves 43 and u to the respective columns.

An outlet pipe II, controlled by a valve 4I, is connectedtothetopoithetowerIandtoapipe I1 controlled by a valve Il. Similarly a pipe Il, controlled by a valve I0, connects the top of the tower I to the pipe 41. Avalve Il is adapted to control delivery of vapor from one or the other of the towers Iand I to a condenser I2 which is cooled by water circulating through the pipe I1. A pipe II delivers the condensed material to any suitable storage receptacle.

A pipe I9 controlled by valves II and Il' connects the tops of the towers I and I with a pipe Il including a valve I2. The pipe Il joins the pipe 2l and permits the return of acid Yvapors escaping from either of the towers I or I toward the end of the sulfur-removing cycle to the other tower, thus avoiding loss of any substantial portion of the acid.

If we assume that the tower I is ready for the sulfur-removing cycle, it is filled with the cupreous treating material l, consisting essentially of copper oxide. It the material to be treated contains insumcient acid. a suitable amount ot acid' is vaporised in the vaporizer 21 and delivered to the bottom of the column I through the connecting pipes to anord a layer of copper compound at the bottom of the column. Vapor from the vaporiaer I3 is introduced. and the sulfur present in the vapor immediately combines with the copper compound, thereby releasing the acid which, being in vapor form, rises to the overlying layer of the treating material, combining therewith to form a copper compound which, in turn, removes the sulfur from the continuing stream oi vapor. The reactions continue over a period of hours during which the layer of copper compound rises gradually in the tower I until the acid has reacted with material in the uppermost layer. At this point, the vapors, including the vaporized acid, are diverted through the pipe Il by suitable manipulation of the valves and are delivered to the bottom of the tower I.

Meanwhile, assuming that the tower I has previously been used, so that all of the material carries the sulfur which has been removed from vapors, the tower is nrst ilushed by the introduction of inert gas from the pipe II. When the hydrocarbon vapors have been removed, oxygen or air, suitably diluted with inert gas, is introduced from the pipe 40. At the temperature prevailing, the oxygen will immediately combine with the sulfur present. The oxidation is, of course, exothermic and must be controlled by the introduction of sufilcient inert gas from the pipe II so that the temperature does not become excessive. The sulfur dioxide formed escapes through the pipe 2t. the valves in the pipes 5 and I8 being closed at this period. When oxidation is complete, the tower is ready to receive the acid vapors which have been flushed from the tower I as previously described. If such acid vapors are not sumcient to cause the initial reaction and the formation of the copper compound, fresh acid vapors may be introduced from the acid vaporizer 21. Vapor from the vaporizer I3 is then diverted to the column I, and the reactions proceed therein as previously described. while the treating material in the tower I is reoxidized in the manner described in connection with the cclumn I. Any number of towers may be employed, the cycle oi treatment and reoxidation of the treating material being maintained so that while desulfurization is effected in one or more of the towers, regeneration of the material is carried out in the others.

The consumption of copper in the operation as described is practically nil, since it remains in the towers and there is no substantially possibility of loss. The reaction during the desuliurization of the material being treated involves only a thin deposit on the surface of the cupreous material, and the undesirable constituent of this fllm, i. e. sulfur, is converted to a volatile material, sulfur dioxide, which escapes as a gas. The only materials used are air and the small amount of acid which may be used in the event that the material treated does not include enough naphthenic acid to form sumcient copper naphthenate with the cupreous material. Most of the acid can be recovered and utilized in the manner described. and small losses thereof are readily made up at relatively slight expense.

The treating material may be packed in simple chambers such as the towers illustrated or in a group of smaller tubes surrounded by a heating ananas manner described with the following ruiil:

Per cent Sulfur in Disiliates ironi- P. mt

B ur Ummm 'rmd "d Omde Crude Gasoline Cut 0. 318 0.050 76. Kerone Cut 0. 637 0. 118 8l. 47 Gas Oil 1.32! 0. m 68. 3

v bisulildes, sulildes and hydrogen suliide.

I claim:

l. 'I'he method of reducing the sulfur content of crude and cracked petroleum distillates which comprises introducing the vapor of an organic carboxylic acid at the bottom of a column consisting essentially of pieces of copper to form a layer of copper soap, directing the distillate in the vapor phase through the layer of copper soap thereby fixing the sulfur present on the copper and releasing the organic acid, and immediately combining the organic acid with the copper of the overlying layer for further desuli'urization of the distillate.

2. The method of reducing the sulfur content of crude and cracked petroleum distillates which comprises introducing the vapor of an organic carboxylic acid at the bottom of a column consisting essentially of pieces of copper to form a layer of copper soap, directing the distillate in the vapor phase through the layer of copper soap thereby fixing the sulfur present on the copper and releasing the organic acid. immediately combining the organic acid with the copper of the overlying layer for further desulfurization of the distillate, and continuing the operation until substantially all of the copper of the column carries sulfur.

3. The/method of reducing the sulfur content of crude and cracked petroleum distillates which comprises introducing the vapor of an organic carboxylic acid at the bottom of a column consisting essentially of pieces of copper to form a layer of copper soap. directing the distillate in the vapor phase through the layer of copper soap thereby fixing the sulfur present on the copper and releasing the organic acid, immediately combining the organic acid with the copper oi the overlying layer for further desuliurization of the distillate, continuing the operation until substan- 8 fimandrevivifyingthespentcoiumnbyogidising the sulfur.

4. The method oi reducing the sulfur content ofcrudeandcrackedpetroleumdistillatesaseet forth in claim l in which the organic acid is naphthenic .acid and the copper soap formed is Y copper naphthenate.

5. The method of reducing the sulfur content of petroleum distillates containing objectionable sulfurous material, which comprises bringing petroleum distillates containing objectionable sulfurous material and an organic carboxylic acid. in the vapor phase, into intimate contact with pieces of cupreous material, whereby the organic acid reacts with said cupreous material to form a copper compound of the acid, and the sulfurous material in the petroleum distillates reacts with the thus-formed copper compound to form stable copper-sulfur compounds and to liberate the organic acid, and bringing the thus-liberated organic acid into intimate contact with more cupreous material to form more copper compound for reaction with more of the vaporized distillates.

6. 'Ihe method of reducing the suliur content of petroleum distillates containing objectionable sulfurous material as set forth in claim 5 in which the organic acid is naphthenic acid and the copper compound formed is copper naphthenate.

7.. The method of reducing the sulfur content of petroleum distillates containing objectionable sulfurous material which comprises passing petroleum distillates containing objectionable sulfurous material, in the vapor phase. into intimate contact with a copper compound of an organic carboxylic acid, whereby the sulfurous material in the distillates reacts with the copper compound to form stable copper-sulfur compounds and to liberate the organic carboxylic acid corresponding to said copper compound. and bringing the thus liberated organic acid into intimate contact with pieces of a cupreous material to form more copper compound for reaction with more of the vaporized distillates.

8. The method of reducing the sulfur content of petroleum distillates containing objectionable sulfurous material as set forth in claim 'I in which the cupreous material is copper.

9. The method of reducing the sulfur content of petroleum distillates containing objectionable sulfurous material as set forth in claim '1 in which the cupreous material is copper oxide.

10. The method of reducing the sulfur content of petroleum distillates containing objectionable sulfurous material as set forth in claim 7 in which the copper compound is copper naphthenate and the organic acid is naphthenic acid.

l1. The method of reducing the sulfur content of petroleum distillates containing objectionable sulfurous material as set forth in claim l0 in which the cupreous material is copper.

12. 'Ihe method of reducing the sulfur content oi' petroleum distillates containing objectionable sulfurous material as set forth in claim 10 in which the cupreous material is copper oxide.

13. 'I'he method of reducing the sulfur content of petroleum distillates which comprises passing the petroleum distillates containing objectionable sulfurous materials, in the vapor phase, into intimate contact with a copper compound of an organic carboxylic acid, whereby the sulfurous material in the distillates reacts with the copper compound to form stable copper-sulfur compounds and to liberate the organic carboxylic acid corresponding to the copper compound, bringim tially all of the copper of the column carries sul- 'le the thusfliberated organic acid into intimate con- '7 tactwithpieceaofacupreoumaterialtoform morecoppercom iorreaetionwithmoreot liberation of organic acid for forming more copper compound until substantially all of the cupreous material has been converted into stable coppersuliur compounds. then discontinuing the' passing of the diatillatea through the cupreous material. and bringing an oxidiaing agent into intimate contact with the copper-sulfur compounds under oxidizing conditions, whereby the-sulfur ci the copper-sulfur compounds is oxidised to sulfur dioxide which escapes as a gas and the cupreous material is regenerated.

14. The method of reducing the sulfur content of peh'oleum distillates containing objectionable sulfurous material as setiorth in claim 13 in which the copper compound is copper naphthenate and the organic acidis naphthenic acid.

15. The method of reducing the sulfur content of petroleum distiliates containing objectionable sulfurous material which comprises forming a bodyoipiecofacoppercompoundoian organic carboxylic acid, forming a body of pieces of a cupreous material -which will react with an organic carboxylic acid to form a copper compound corresponding to the ,organic carboxylic acid, and passing the petroleum distillates containing the objectionable in the vapor phase, into intimate contact successively with the body of copper compound and then with the body ci cupreous material, the suliurous material in the distillates reacting with the copper compound to form stable coppersulfur compounds and to liberate the organic carboxylic acid corresponding to the wm compound, and the thus-liberated organic carboxylic acid reacting with the body oi' cupreous material to form the corresponding copper compound for reaction with more of the suliurous material in the vaporized distillates.

16. The method of reducing the sullur content of petroleum distillates containing objectionable sulfurous material which comprises forming a body of pieces of a copper compound of an organic :,aoaaee I ,macadam-ninguna;

40 Number piaceaofa cupreous material whichwlllreaotwithan organiccarboxylicacidtotormaooppercnpoundcorrespondingtotheorganiccarboaylic 'lively with the body of copper compound and then with the body of cupreous material. the sulfuroul material in the distillates reacting with the copper compound to iorm stable copper-suliurcompounda and to liberate the organic carboxylic acid corresponding to the copper compound, and the thus-liberated organic carbonlic acid reacting with the body oi.' cupreous material to form the corresponding copper compound for reaction with more of the suliurous material in the vaporized distillates, continuing to pass sulfurous containing petroleum distillates, in a vapor phase. through the said bodies with successive reaction of the suliurous material with the copper compound and liberation of the organic acid, forming more copper compound until substantially all oi the cupreous material has been convertcd into stable copper-sulfur compounds. then discontinuing the passing oi the distillatcs through the said bodies, and bringing an oxidizing agent into intimate contact with the coppersulfur compounds under oxidizing conditions,

whereby the sulfur of the copper-sulfur ccmpounds is oxidized to suliur dioxide which `.scapea as a gas and the cupreous material is regenerated.

- CHARLES O. HOOVER.

REFERENCES CITED The following references are oi' record in the ille of this patent:

UNITED STATES PATENTS Name Date 1,587,491 Cross June 1, 1928 1,937,113 Gray Nov. 28, 1933 2,066,213 Merchant Dec. 29, 1936 2,297,620 Henderson Sept. 29, 1942 u FOREIGN PATENTS Number Country Date 328,875 Great Britain May 8, 1930 

1. THE METHOD OF REDUCING THE SULFUR CONTENT OF CRUDE AND CRACKED PETROLEUM DISTILLATES WHICH COMPRISES INTRODUCING THE VAPOR OF AN ORGANIC CARBOXYLIC ACID AT THE BOTTOM OF A COLUMN CONSISTING ESSENTIALLY OF PIECES OF COPPER TO FORM A LAYER OF COPPER SOAP, DIRECTING THE DISTILLATE IN THE VAPOR PHASE THROUGH THE LAYER OF COPPER SOAP THEREBY FIXING SULFUR PRESENT ON THE COPPER AND RELEASING THE ORGANIC ACID, AND IMMEDIATELY COMBINING THE ORGANIC ACID THE COPPER OF THE OVERLYING LAYER FOR FURTHER DESULFURIZATION OF THE DISTILLATE. 